Deposition of thin films is one of the key processes in semiconductor manufacturing. A typical wafer goes through deposition of several thin films, some of which may completely or partially remain in the final electronic device. Certain types of films are deposited using liquid precursors, for example tetra-ethyl-ortho-silicate (TEOS). TEOS provides excellent conformality of the deposited silicon dioxide in comparison to gaseous precursors.
Films deposited using TEOS or other liquid precursors are often deposited using a plasma enhanced deposition chemical vapor deposition (PECVD) process. PECVD processes based on liquid precursors typically involve exposing a substrate to precursor vapor and an oxidant, such as oxygen or ozone, in the presence of plasma. Such processes often generate many particles during precursor flow stabilization. Particles may be generated due to the condensation and thermal decomposition of the precursors inside the chamber. The problem may be become even more severe due to transient ignition envelopes, i.e., periods of building up plasma.